Does rilmenidine act in vivo on central alpha 2-adrenoceptors modulating noradrenaline release?

Noradrenaline release evoked by electrical stimulation was recorded in the rat hypothalamus by in vivo electrochemistry. Rilmenidine (0.3-10 mg kg-1 i.v.) did not diminish this evoked release while clonidine induced a dose-dependent decrease. These results further suggest that the antihypertensive action of rilmenidine is not mediated by central alpha 2-adrenoceptors and might explain why, unlike clonidine, rilmenidine does not have sedative effects.